º£½ÇÆƽâ°æ

Interleukin-1 receptor accessory protein (IL1RAP) is selectively expressed on both bulk blasts and leukemic stem cells (LSCs) in acute myeloid leukemia (AML), while its expression is virtually absent on normal hematopoietic stem cells (HSCs), making it an appealing target for chimeric antigen receptor (CAR) T cell therapy. Methods: We developed a novel IL1RAP-targeting CAR-T cells using a single-chain Fab (24scFab) fused to CD28 and CD3¦Æ costimulatory domains. CAR-T cells with a mutated IL1RAP-binding paratope were also generated as a control by introducing two point-mutations in the complementarity determining region (CDR) loops of the 24scFab domain. We tested the CAR-T cells in cell line-derived (CD) and patient-derived (PD) xenografts (X). To address persistence and activity of IL1RAP CAR-T cells, we then tested two approaches. First, we mutated two of the three immunoreceptor tyrosine-based activation motifs (ITAMs) within the CD3¦Æ domain (i.e., IL1RAP-1XX CAR-T). Second, we co-administered a synthetic miR-142 mimic (M-miR-142), previously shown to enhance T cell antileukemic activity, with IL1RAP CAR-T cells to AML xenografted mice. Results: IL1RAP CAR-T cells demonstrated a potent antileukemic activity in both AML CDX and PDX models. Target specificity was confirmed by the complete loss of function of IL1RAP-mutated CAR-T cells. IL1RAP-1XX CAR-T cells improved T cell persistence in vitro but failed to demonstrate therapeutic benefit compared with IL1RAP CAR-T cells in vivo. We previously reported that leukemic cell growth suppresses miR-142 biogenesis, thereby hindering the metabolic switch and impairing host T cell antileukemic activity; this was rescued by administration of M-miR-142. Thus, we hypothesized a similar impact of leukemic cells on CAR-T and that M-miR-142 treatment could rescue it and enhance the IL1RAP CAR-T cell antileukemic activity. We showed that both CDXs and PDXs receiving M-miR-142 and IL1RAP CAR-T lived significantly longer than those receiving scrambled oligonucleotide and IL1RAP CAR-T or mutated CAR-T controls (median survival of PDX: 78 vs 51 vs 24?days). Conclusions: We have identified a potentially novel strategy to enhance CAR-T cell persistence and efficacy in AML by counteracting a leukemia-induced, microRNA-deficiency mediated mechanism of immune suppression.

Background: Recurrent/metastatic head and neck squamous cell carcinoma ((R/M) HNSCC) represents one of the most aggressive and immunosuppressive cancers. Despite the introduction of immune checkpoint inhibitors (ICIs), only a limited number of patients obtain long-term benefits. In (R/M) HNSCC patients, the antitumor immune response is defective, conferring resistance and promoting tumor progression. Therefore, the identification of novel biomarkers for superior clinical outcomes and easily accessible in standard clinical settings is still an unmet clinical need. Methods: Blood liquid biopsies obtained from (R/M) HNSCC patients undergoing pembrolizumab therapy (monotherapy or in combination with chemotherapy) were analyzed by flow cytometry to evaluate the levels of circulating immunosuppressive regulatory T cells (Tregs) and myeloid derived suppressor cells (MDSCs), at baseline and during therapy. Correlations between these immunosuppressive immune cell subsets and clinical parameters (clinical response rate, progression-free survival (PFS), overall survival (OS) and performance status (PS)) were performed. Results: Univariate analysis showed that before therapy, higher circulating levels of both CD137?Tregs and LOX-1?PMN-MDSCs, identified patients with significantly worse survival. Furthermore, CD137?Tregs resulted also positively correlated with worse PS, while high levels of LOX-1?PMN-MDSCs negatively affected response to pembrolizumab, with a significant increase in non-responsive patients during therapy. Interestingly, both CD137?Tregs as well as LOX-1?PMN-MDSCs exerted a higher immunosuppression on T cell proliferation than CD137?Tregs and LOX-1?PMN-MDSCs, respectively. Multivariate analysis revealed that the circulating LOX-1?PMN-MDSC subset resulted as an independent prognostic factor for survival by multivariate analysis, as confirmed in an independent validation cohort. Conclusions: The levels of blood circulating LOX-1?PMN-MDSCs may be proposed as non-invasive biomarkers to predict clinical outcomes of (R/M) HNSCC patients developing resistance to immunotherapy, improving patient selection and suggesting novel personalized therapies.

PURPOSE Chronic inflammation contributes to tumor initiation, progression, and immune escape. Neutrophils are the major component of inflammatory response and participate in the tumorigenesis process. However, compared to other immune cells in the tumor microenvironment of laryngeal squamous cell carcinoma (LSCC), neutrophils, especially the tumor-associated neutrophils (TANs), have not yet been comprehensively explored. The mechanism for regulating the crosstalk between TANs and tumor cells still remains unclear. MATERIALS AND METHODS The distribution profiles and phenotypic features of neutrophils and other inflammatory immune cell populations from a large LSCC patient cohort were systemically analyzed. Co-culturing of peripheral blood associated neutrophils (PANs) and TANs with PBMCs was performed, and the immunosuppression effect on T-cells was examined. RESULTS LSCC microenvironment is highly inflammatory with remarkable TANs infiltration, which is often associated with unfavorable prognosis and advanced clinical stage. We find that TANs in LSCC display morphologically immature and lower apoptosis, exhibit distinctively immunosuppressive phenotype of high PD-L1, and suppress CD8+ T lymphocytes proliferation and activation. We subsequently discover that PD-L1+TANs induced by LSCC-derived GM-CSF potently impair CD8+ T-cells proliferation and cytokines production function, which are partially blocked by a PD-L1-neutralizing antibody. Clinical data further support GM-CSF as an unfavorable prognostic biomarker and reveal a potential association with inflammatory immune cell infiltration, in particular neutrophils. CONCLUSION Tumor-infiltrating PD-L1+ neutrophils induced by LSCC-derived GM-CSF suppress T cell proliferation and activation in the inflammatory microenvironment of LSCC and predict unfavorable prognosis. These TANs cripple antitumor T cell immunity and promote tumor progression. Our findings provide a basis for targeting PD-L1+TANs or GM-CSF as a new immunotherapeutic strategy for LSCC.